Horiguchi Gen, Aoki Takafumi, Ito Hiromoto
Department of Restorative Medicine of Neuro-musculoskeletal System, Orthopaedic Surgery, Graduate School of Medicine, Nippon Medical School, Japan.
J Nippon Med Sch. 2011;78(4):208-13. doi: 10.1272/jnms.78.208.
The main cause of carpal tunnel syndrome (CTS) remains unknown. Stiffness of the subcutaneous area of the volar aspect of the carpal tunnel is present in many patients and suggests that the stiffness of muscles attached to the transverse carpal ligament is increased. We performed an electrophysiological study to investigate muscle activities and to clarify whether the stiffness of muscles attached to the transverse carpal ligament is involved in the pathogenesis of CTS. The subjects of this study included 16 patients with early CTS showing no motor dysfunction. Both thenar muscles (opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis) and hypothenar muscles (opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis) were investigated. Surface electrodes were placed on each muscle, and maximum voluntary contractions with the thumb and little finger in opposition were maintained for 3 seconds in all patients and in 7 control subjects. Electromyographs were subjected to fast Fourier transform analysis, and the root mean square (RMS) and the mean power frequency (MPF) were determined for each muscle. The RMS of the opponens pollicis was significantly less in hands affected by CTS (292.8 µV) than in healthy hands (405.9 µV). The RMS did not differ between affected hands and healthy hands for the other 2 thenar muscles but did differ significantly for the hypothenar muscles. The MPF did not differ between affected hands and healthy hands for any muscle. The results show that electrophysiological differences are present among muscles innervated by the median nerve and that hypothenar muscles originally unrelated to median nerve dysfunction are also affected in early CTS. These results suggest that modulation of muscles attached to the transverse carpal ligament is involved in the pathogenesis of CTS.
腕管综合征（CTS）的主要病因仍不明确。许多患者腕管掌侧皮下区域存在僵硬感，这表明附着于腕横韧带的肌肉僵硬程度增加。我们进行了一项电生理研究，以调查肌肉活动，并阐明附着于腕横韧带的肌肉僵硬是否与CTS的发病机制有关。本研究的对象包括16例早期CTS患者，这些患者未表现出运动功能障碍。对鱼际肌（拇对掌肌、拇短展肌和拇短屈肌）和小鱼际肌（小指对掌肌、小指展肌和小指短屈肌）均进行了研究。在所有患者和7名对照受试者中，将表面电极置于每块肌肉上，使拇指和小指对掌进行最大自主收缩并持续3秒。对肌电图进行快速傅里叶变换分析，并测定每块肌肉的均方根（RMS）和平均功率频率（MPF）。在CTS患侧手部，拇对掌肌的RMS（292.8 μV）显著低于健侧手部（405.9 μV）。另外两块鱼际肌患侧与健侧手部的RMS无差异，但小鱼际肌的RMS在患侧与健侧手部之间存在显著差异。任何肌肉患侧与健侧手部的MPF均无差异。结果表明，由正中神经支配的肌肉之间存在电生理差异，并且在早期CTS中，原本与正中神经功能障碍无关的小鱼际肌也受到了影响。这些结果提示，附着于腕横韧带的肌肉调节与CTS的发病机制有关。
